CT scan for kidney stones
Unlike ultrasound and X-ray, CT sees stones in any part of the ureter, including X-ray negative urate ones, and accurately measures them: size to the millimeter, density in Hounsfield units (less than 1000 HU - ESWL is effective, more - contact lithotripsy is preferable), distance from the skin to the stone (for ESWL), anatomy of the calyces (for PCNL). Urologists at the clinics below plan a type of lithotripsy using this CT scan and monitor the result after 4–6 weeks. The examination also shows cysts, large tumors, abnormalities (duplication, horseshoe kidney) and signs of pyelonephritis; CT urography with contrast is performed to evaluate function and tumors.
Indications
- urolithiasis, renal colic - search for stones, their size and density;
- hydronephrosis, disturbance of urine outflow - level and cause of obstruction;
- tumors of the kidneys, pelvis, ureters, bladder - detection and staging;
- blood in urine of unknown cause;
- anomalies in the development of the kidneys and urinary tract, planning of operations (PNL, pyeloplasty);
- kidney injury, cysts, abscesses, paranephritis;
- renal artery stenosis, renovascular hypertension (CT angiography).
What is MSCT
Multislice computed tomography is a layer-by-layer X-ray study in which detectors receive dozens of sections up to 0.5–1 mm thick in one revolution of the tube, and a computer builds a three-dimensional image of the organ. MSCT is performed in 5-15 minutes, accurately shows bones, lungs, stones, hemorrhages, tumors and vessels (with contrast), and is often the method of choice for trauma and acute conditions when MRI is too long or contraindicated.
Preparation and contrast
Non-contrast MSCT does not require preparation. Before a study with intravenous contrast, a test for creatinine (kidney function) and the absence of an allergy to iodine are required; 4–6 hours without eating; When taking metformin, agree on a break with your doctor. Contrast (Unigexol) is administered using an automatic injector; a feeling of warmth for 1–2 minutes is normal. To examine the abdominal and pelvic organs, oral contrast is used, which is drunk 30–60 minutes before the scan. Remove metal objects from the examination area. The radiologist’s conclusion is completed within 1–2 hours, the images are issued on film and disk.
Radiation exposure and safety
Modern devices use low-dose protocols; the dose for one study is comparable to several months of natural background and does not accumulate dangerously when prescribed appropriately. MSCT is not performed on pregnant women (except for vital indications); for children - according to strict indications with a minimum dose. Iodine contrast is contraindicated in severe renal failure, iodine allergy and uncontrolled hyperthyroidism. Pacemaker and metal implants are not a contraindication, unlike MRI.
